The invention relates to a brake booster for vehicles. To increase the braking action in motor vehicles, brake boosters disposed between the brake pedal and the brake system are provided. Their task is to amplify the force fed to the pedal. Known brake boosters include a brake valve that is opened via the brake pedal and as a result causes a medium that is under pressure to act upon a booster piston, which in turn generates a braking force. A slide used in these brake valves is typically supported at least two points. Because of machining tolerances, the slide may not be located centrally with respect to the valve seat embodied as its counterpart, and therefore must be pressed into the valve seat by a sufficiently great spring force to prevent leakage.